Question

4.3.2 test (cst): electromagnets
the diagram shows an electromagnet made with copper wire, a steel nail,
and a 1.5 v battery. which change would make this electromagnet stronger?
a. wrap more coils of wire around the nail.
b. reverse the direction of the battery.
c. disconnect the battery from the copper wire.
d. replace the steel nail with a wooden stick.

Explanation:

• Option A: Wrapping more coils of wire around the nail increases the number of loops through which the current passes. According to the principles of electromagnetism, the strength of an electromagnet is directly related to the number of wire coils (when other factors like current are considered). More coils mean a stronger magnetic field.
• Option B: Reversing the direction of the battery changes the polarity of the electromagnet (swaps the north and south poles) but does not affect its strength.
• Option C: Disconnecting the battery from the copper wire stops the current flow. Without current, there is no electromagnet (as the magnetic field is generated by the current - carrying wire around the core).
• Option D: Replacing the steel nail (a ferromagnetic material) with a wooden stick (a non - ferromagnetic material) would result in a very weak or no magnetic field. Ferromagnetic materials enhance the magnetic field of an electromagnet.

Answer:

A. Wrap more coils of wire around the nail.